#if <TRADITIONAL C HEADERS>
#include <time.h>
namespace std {
using ::asctime;
using ::clock;
using ::clock_t;
using ::ctime;
using ::difftime;
using ::gmtime;
using ::localtime;
using ::mktime;
using ::size_t;
using ::strftime;
using ::time;
using ::time_t;
using ::tm;
}
#endif

Including this header also ensures that the names declared with external linkage in the Standard C Library header are declared in the std namespace. In this implementation, the names may or may not also be declared in the global namespace, depending on the specific translation environment.